The minimum intensity of sound is zero at a point due to two sources of nearly equal frequencies when

Options

A. two sources are vibrating in opposite phase
B. The amplitude of two sources are equal
C. at the point of observation, the amplitudes of two S.H.M. produced by two sources are equal and both the S.H.M. are along the same straight line
D. Both the sources are in the same phase

Answer

C

Explanation

If two waves of nearly equal frequency superpose, they give beats if they both travel in straight line and `I_(min)=0` if they have equal amplitudes.